I cannot comment on Steinbock's English translation, since I have not seen it. However, the original German edition, while certainly an essential text, would have been improved had it included the introductory lectures that Husserl gave to the series included here. I believe that these introductory sections were inlcuded as a supplementary text to Husserliana XVII (Formale und transzendentale Logik). The French translation (published by Jerome Millon) rectifies this by adding the text from Hua XVII at the beginning of the translation.

Steinbock's translation is the first 'organic' translation of the lectures on Active and Passive Synthesis -- it includes the introductory lectures and the lectures on active synthesis that have been published in Hua XXXI (I think!). His translation is fairly accurate according to my German-speaking sources, and the introduction to the volume is quite good. Also, it should be noted that all of the 20/21 versions of the lectures, where they differ from the 26 version, are included, as are a few short essays on genetic method which are scattered throughout the Husserliana series. All in all, an understanding effort.